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342 COLLEGE ENTOMOLOGY
rior end of abdomen with anal lobes, valves, ring, or pygidium and variable
arrangements of spines, pores, glands, chitinized areas, and modified hairs.
The young males are similar to the females but usually after the second molt
they form a cocoon or remain under the shell and go through a more complete
metamorphosis, emerging as minute or small, active, apterous or winged insects
with regularly segmented bodies, well-developed antennre., 10- or moresegmented;
(branched in the African Neomargarodes Green); prominent,
simple eyes or ocellanre in single or double groups; abortive mouth parts; one
pair of delicate wings of very simple venation; and a pair of rudimentary hind
wings or halteres; two long anal hairs supporting wax in life; and a long penis.
In some species both winged and apterous forms are present, and in others
males have not been observed at all.
Scale insects are free-living on the roots or tops of plants or inhabit galls or
pseudogalls and are frequently found in ants' nests. Like aphids and some
FIG. 117. 1st instar larva of the coccid. Wallieriana ovilla Green. Its long silken filaments
enable it to be carried by the wind like thistle-down. (Redrawn from Green.)
other members of the HOMOPTERA, scale insects, with the exception of the
armored forms (DIASPIDIDJE), secrete quantities of honeydew which covers
the foliage of the hosts and the vegetation, soil, and other objects beneath the
hosts. This sticky material is not only unsightly and obnoxious but is the food
of a black smut fungus which, with accumulating dust and the countless
numbers of ants, flies, bees, wasps, and other insects attracted by the sweet
exudate, makes the presence of most scale insects very undesirable. However,
it should be pointed out that honeybees convert honeydew into honey and
that this secretion has otherwise been utilized to some extent as a food for
human beings. Coccids are cosmopolitan in distribution, and about 2,500